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4

Suppose that 90% of people are right-handed. What is the probability that at most 6 of a random sample of 10 people are right-handed?

It is given in the question that,

90% of the people are right handed

Let p denotes the probability of people that are right handed and q denotes the probability of people that are left handed

∴

And,

Now, by using the binomial distribution probability of having more than 6 right handed people can be given as:

Hence, the probability of having more than 6 right handed people:

= 1 – P (More than 6 people are right handed)

=

4

12

Suppose we have four boxes A, B, C and D containing coloured marbles as given below:

Box | Marble colour | ||

Red | White | Black | |

A | 1 | 6 | 3 |

B | 6 | 2 | 2 |

C | 8 | 1 | 1 |

D | 0 | 6 | 4 |

One of the boxes has been selected at random and a single marble is drawn from it. If the marble is red, what is the probability that it was drawn from box A?, box B?, box C?